COKE MANUFACTURE. 567 
of the volatile matter of the coal. By this means the coking process 
acts from different parts of the charge at the same time, and a perfect 
coking more surely attained. In the construction of ovens, the thick- 
ness of the bed or prism of coal in the oven is of the greatest import- 
ance. The higher the coking property and the proportion of volatile 
matter, the thicker may the bed of coal be made, and the lower the 
degree of coking power, or the drier the coal, the thinner must the 
prism of coke be made to secure good results. Thus with good coking 
coals the prism of coal may be 3 or 4 feet in thickness, and then only 
heated on one side, but with the drier coals, even when heated on all 
sides, the prism must be much smaller, 3 feet to 27 inches, as in the 
Belgian ovens. The disregard of this fact is the cause of much ill 
success in the planning and making of coke ovens. ‘The first and most 
important consideration is the character of the coal, and the second, 
the form and size of oven best adapted to the circumstances. 
Coke ovens differ very greatly in their form, size, construction and 
mode of heating, and for convenience they may be divided into two 
principal classes: 
1. Those in which the walls of the oven are not hentia’, and air is 
admitted into the coking chamber itself to allow the combustion of the 
gases evolved from the coal, and to maintain the heat necessary for the 
operation, as in the ordinary ‘ bee hive” oven. 
2. Those in which the bottom, the walls, or both, are heated by — 
the combustion of fuel on the outside, generally of the gases from the 
coal which are burnt in flues in the walls themselves. In some forms 
the combustion is begun in the furnace itself by the admission of air, 
as the Jones and Francais oven, but usually it is confined to the flues 
into which the air is admitted, as in the ovens of the Belgian type. 
First Ciass.—Bee-hive, Baker’s or Round oven. This is one of the 
oldest forms of coke oven, and is still used to some extent in France 
and Germany, where it is known as the English or Baker’s oven. In 
England, however, it is almost exclusively employed, and while it is 
the most common oven in the United States, large numbers of the im- 
proved forms are now being introduced. 
A very good example of the bee-hive ovens is in use at the Kemble 
Tron Co.’s works, Riddlesburgh, Penn. 
The ovens are circular vaulted chambers, like a baer oven, 12 
feet in interior diameter, and 6 feet in height from the bottom to the 
